Bovine Brucellosis: An Epidemiological Study at Chittagong, Bangladesh

An epidemiological survey was conducted to identify probable risk factors and prevalence of brucellosis in commercial and backyard dairy cows at Chittagong, Bangladesh. A total of 500 milk samples were collected (250 commercial and 250 backyards) for Milk Ring Test (MRT). The MRT positive cows were subjected to sera collection and Rose Bengal Plate Test (RBPT) and indirect ELISA were done for confirmatory diagnosis. The overall seroprevalence of brucellosis in cattle was 5% (7.6% in commercial and 2.4% in backyard). Significantly higher (P<0.05) prevalence was found in the zero grazing (5.74%), pregnant cows (7.53%) and cows with history of retained placenta (7.89%) or abortion (5.88%) or both (11.76%) than non-pregnant (2.68%) and without any reproductive disorder (4.44%). A total of 420 farm attendants and owners were interviewed where 93.55 and 99.08% commercial and backyard personnel were found to have no knowledge of brucellosis and 9.67 and 87.77% consumed raw milk and yogurt respectively were highly vulnerable to zoonotic brucellosis. The results showed that brucellosis is widely distributed locally, underscoring the need for further studies including biovar determination

Sub-clinical mastitis prevalent in dairy cows in Chittagong district of Bangladesh: detection by different screening tests

Aim: Mastitis is recognized as one of the most costly health disorder affecting dairy cows. An epidemiological study was carried out at some selected farms in Chittagong district of Bangladesh to determine the prevalence and risk factors of sub-clinical mastitis (SCM) in dairy cows. Materials and Methods: For conducting the study, some dairy farms of Chittagong were selected from urban and periurban areas by stratified random sampling. A total of 444 quarter samples of 111 (56 from commercial dairy farms and 55 from backyards) lactating dairy cows were considered. Sub-clinical mastitis (SCM) was determined using three different indirect screening tests: California Mastitis Test (CMT), White Slide Test (WST) and Surf Field Mastitis Test (SFMT). Sensitivity and specificity were also determined to measure the accuracy of those tests. Results: The prevalence of SCM by CMT, WST and SFMT were 32.43% (n=144), 33.56% (n=149) and 31.53% (n=140), respectively. Distribution of SCM in relation to different variables at quarter level and animal level was also recorded. The prevalence of SCM was significantly (P<0.05) higher in aged, high yielding cows in addition with history of periparturient diseases, without dry cow therapy both at quarter and animal level. A significantly (p<0.01) higher prevalence (48.98%) of SCM was observed in higher parity number (>4) than others at quarter level. No significant difference (P>0.05) was found in relation to breed. Using CMT as a gold standard, sensitivity and specificity of WST and SFMT were also calculated at 95% confidence interval. The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, positive predictive value, negative predictive value and disease prevalence by WST and SFMT were comparable. Conclusion: This study recommends that regular screening of sub-clinical mastitis will reduce the prevalence of sub-clinical mastitis. The most effective way to control sub-clinical mastitis is to take preventive measures such as regular cleaning of the floor, keeping the udder clean, milkman's cleanliness, dry cow therapy specially in high yielding dairy cows